Irwindale is a city in the San Gabriel Valley, in Los Angeles County, California. The population was 1,422 at the 2010 census, down from 1,446 at the 2000 census. The ZIP Codes serving the area are 91010, which is shared with Duarte, 91702, which is shared with Azusa, and 91706, which is shared with Baldwin Park. With relatively few residents, Irwindale consists mostly of rock quarries, which are the major revenue source for the city.